U.S. patent number 5,071,406 [Application Number 07/389,356] was granted by the patent office on 1991-12-10 for limacon geometry balloon angioplasty catheter systems.
Invention is credited to G. David Jang.
United States Patent |
5,071,406 |
Jang |
* December 10, 1991 |
Limacon geometry balloon angioplasty catheter systems
Abstract
Disclosed is an angioplasty catheter comprising a catheter shaft
having a distal end and at least one, and preferably two,
angioplasty balloons on the distal end of the catheter shaft,
wherein the distal end of the catheter and the balloons are formed
from a single monolithic piece of polymer material. The distal end
of the catheter may also include additional balloons formed from
the same piece of polymer material. Each of the balloons is
separately inflatable and deflatable by virtue of a separate lumen
running through the catheter shaft to the balloon.
Inventors: |
Jang; G. David (Redlands,
CA) |
[*] Notice: |
The portion of the term of this patent
subsequent to November 28, 2006 has been disclaimed. |
Family
ID: |
26724576 |
Appl.
No.: |
07/389,356 |
Filed: |
August 3, 1989 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
47049 |
May 6, 1987 |
4958634 |
|
|
|
Current U.S.
Class: |
604/101.01;
604/913; 606/192; 606/194 |
Current CPC
Class: |
A61M
25/1034 (20130101); A61M 25/104 (20130101); A61M
2025/1079 (20130101); A61M 2025/1072 (20130101); A61M
25/1029 (20130101) |
Current International
Class: |
A61M
25/00 (20060101); A61M 29/02 (20060101); A61M
029/00 () |
Field of
Search: |
;604/21,96-103
;606/191-197 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Yasko; John D.
Assistant Examiner: Gutowski; Anthony
Attorney, Agent or Firm: Knobbe Martens Olson & Bear
Parent Case Text
This application is a continuation of application Ser. No. 047,049,
filed 5-6-87, now U.S. Pat. No. 4,958,634.
Claims
What is claimed is:
1. An angioplasty catheter, comprising:
a catheter shaft having a proximal end and a distal end;
at least two independently inflatable and independently deflatable
angioplasty balloons at the distal end of said catheter, each said
balloon having a balloon wall and having a length and a different
maximum inflated diameter, wherein said balloons and said distal
end of said catheter shaft comprise a single, integral monolithic
piece of polymer material and wherein said balloons are
eccentrically positioned with respect to each other, wherein said
balloons comprise a first balloon and a second balloon located on
opposite sides of said catheter shaft, wherein said first balloon
and said second balloon are only in part axially coextensive.
2. The catheter shaft of claim 1, wherein at least two of said
balloons extend from the side of the catheter shaft so that said
shaft forms a part of the wall of said balloons.
3. The catheter of claim 1 wherein said first balloon and said
second balloon extend from opposite sides of said catheter shaft,
so that at least part of said first balloon is directly opposite at
least part of said second balloon.
4. An angioplasty balloon catheter, comprising:
a catheter shaft having a proximal end, a longitudinal axis, and a
distal end;
first and second angioplasty balloons on the distal end of said
catheter shaft, each said balloon having a longitudinal axis,
wherein said balloons have different predetermined maximum inflated
diameters and are joined to said catheter shaft along the length of
said balloons so that catheter shaft forms a part of the wall of
said balloons, wherein said balloons are only in part coextensive
along said catheter shaft.
5. The catheter of claim 4, wherein said axes of said balloons are
eccentric with respect to said axis of said catheter shaft.
6. An angioplasty catheter, comprising:
a catheter shaft having a proximal end and a distal end with at
least two lumens extending therethrough; and
first and second angiplasty balloons on the distal end of said
catheter shaft, wherein said balloons and said distal end of said
catheter shaft are formed from a single monolithic piece of polymer
material by sealing shut two of said lumens and heating the distal
end of said catheter shaft, then internally pressurizing said
sealed lumen to expand at least a portion of said distal end of
said catheter shaft into said balloons, wherein said balloons are
eccentric with respect to said catheter shaft and one of said
balloons extends only in part along the same length of said
catheter shaft as another of said balloons and has a different
maximum inflated diameter than said other balloon.
7. The catheter of claim 6, wherein the maximum inflated working
diameter of each balloon is substantially uniform over the length
of such balloon.
8. The catheter of claim 6, wherein said catheter shaft extends
through said balloons, further comprising a lumen extending the
length of said catheter shaft for receiving steerable
guidewire.
9. The catheter of claim 6, further comprising:
an axial torque guidewire extending through one of said lumens and
out of the distal end of said first balloon and said catheter,
wherein the distal end of said first balloon is sealed to said,
guidewire.
10. An angioplasty catheter, comprising:
a catheter shaft having an axis, a distal end, and a proximal
end;
a first independently inflatable angioplasty balloon on a first
side of the distal end of said shaft;
a second independently inflatable angioplasty balloon on a second
side of the distal end of said shaft, wherein said first balloon
and said second balloon are only in part axially coextensive on
said catheter shaft.
11. The catheter of claim 10 wherein said first and second balloons
and said distal end of said catheter shaft comprise a single
integral piece of polymer material.
12. The catheter of claim 10, wherein said first balloon and said
second balloon are on opposite sides of said catheter shaft and
wherein at least part of said first balloon is directly opposite at
least part of said second balloon.
13. The catheter of claim 10, wherein the maximum inflated diameter
of said first balloon is less than the maximum inflated diameter of
second balloon.
14. The catheter of claim 13, wherein a portion of said first
balloon is distal of said second balloon.
15. The catheter of claim 10, wherein the wall of each balloon is
joined to the distal end of said catheter shaft along substantially
the entire length of each said balloon.
16. The catheter of claim 15 or 13, further comprising a third
balloon on said catheter shaft.
Description
BACKGROUND OF THE INVENTION
This invention relates to balloon angioplasty catheters having
limacon geometry and a method of making same, and to angioplasty
catheter systems utilizing multiple balloons, and to angioplasty
procedures utilizing those catheters.
Coronary angioplasty has emerged as the only viable present
alternative to bypass surgery for revascularization of stenotic and
occluded coronary arteries. Although transluminal angioplasty has
application in peripheral artery disease, it is most widely used in
the treatment of coronary artery disease. Unlike bypass surgery,
percutaneous angioplasty does not require general anesthesia,
cutting of the chest wall, extracorporeal perfusion, or transfusion
of blood. Percutaneous coronary angioplasty is not only less
invasive and less traumatic to the patient, it is also less
expensive because the angioplasty patient will have a shorter
hospital stay and shorter post-procedure recovery time.
Percutaneous transluminal angioplasty is performed by making a skin
puncture with a specially-designed needle in one of the groins, and
then introducing a guiding catheter (typically 8 or 9 French size)
into the aorta and coronary artery orifice. A smaller caliber
catheter which has a built-in inflatable and deflatable balloon of
predetermined size and diameter is passed through the guiding
catheter which is positioned in the opening of a target artery.
This balloon catheter (with the balloon totally deflated by
negative pressure) is advanced inside the target artery toward the
point of obstruction that needs to be dilated. With the balloon
portion of the catheter properly positioned inside the obstructed
segment of the artery, under X-ray fluroscopic observation, the
balloon is inflated by injecting contrast media mixed with saline
at a pressure sufficient to overcome the resistance of the
arterosclerotic plaque of the obstructed segment.
During the guiding catheter manipulation and especially while the
balloon catheter is being advanced into the narrowed segment of the
artery, X-ray fluoroscopy is used extensively. However, because one
cannot ordinarily see the anatomy of an artery under X-ray
fluoroscopy, contrast material is used. When contrast media is
injected into an artery, details of the arterial anatomy are
briefly visible until the contrast material flows away with the
blood flow through the artery. Radiographic arteriograms are
recorded during that brief moment of visualization. If the anatomic
structures are complex and negotiating a particular arterial
channel with the balloon catheter is difficult, frequent contrast
injections during the procedure are necessary. However, there are
limits to the amount of contrast material one can use in a given
patient. For instance, the upper limit of Renografin-76 in a normal
individual is approximately 3 c.c.'s per kilogram of body weight.
The tolerance of a physically-ill individual may be substantially
less. Excessive amounts of contrast material can be toxic to the
kidneys, liver and brain.
By inflating the balloon in the stenosis multiple times over a
period of between 20-30 seconds and one or two minutes (allowing
blood flow between inflations), the desired dilation of the
obstructed segment of the artery can be achieved. When the desired
results have been obtained by balloon inflations, the guiding
catheter and the balloon catheter (with the balloon completely
deflated with negative pressure) are withdrawn from the artery and
the procedure is successfully terminated.
Arterosclerotic coronary artery disease is not curable. Both bypass
surgery and balloon angioplasty are considered palliative
treatments. Recurrence of disease after bypass surgery or coronary
angioplasty is prevalent, and repeat procedures are not uncommon
due to the nature of the disease. A patient may initially develop
single-vessel coronary artery disease and then slowly progress into
multiple-vessel disease over the years. Medications, bypass surgery
or angioplasty do help to relieve the symptoms, but they generally
cannot prevent a gradual progression of the disease.
Because the cost of bypass surgery is 2 to 2.5 times the cost of
angioplasty, and because bypass surgery is more invasive and more
traumatic, requiring longer hospital stays and longer
post-operative recuperation, future demand for angioplasty is
expected to grow as physician skill and equipment technology
expands. It has been estimated that the number of coronary artery
angioplasties performed in the United States will double or triple
to 450,000 or 500,000 cases per year by the early to mid 1990's. It
also has been estimated that the number of multiple-vessel
angioplasty cases will be from 2 to 2.5 times the number of
single-vessel angioplasty cases. This will be a dramatic change
from the situation in 1986 in which 70 to 80 percent of the
coronary angioplasty cases are single-vessel dilations. The
expected future growth of multi-vessel coronary angioplasty has
serious technical and patient care implications. Present-day
coronary angioplasty technology is based on the original single
balloon concept which was designed to tackle single-vessel disease
and thus single-vessel dilations. However, the single balloon
technology is inadequate to meet the requirements of most
multi-vessel disease situations.
During a typical coronary angioplasty, most of the procedure time
is spent in certain preliminary steps that are necessary before the
balloon can be inflated inside the obstructed segment of a target
artery. In fact, the real job of dilating a vessel takes less than
20 percent of the total procedure time. The preliminary steps
include patient (aseptic) preparation, groin preparation and needle
puncture, insertion of the guidewire into the artery to introduce
the guiding catheter, arterial heparinization, manipulation of the
guiding catheter to cannulate the target coronary orifice,
preliminary arteriography using contrast media injection into the
artery and taking radiographic cine. Moreover, the balloon catheter
must be prepared before it can be introduced into the target artery
through the lumen of the guiding catheter. Preparation of the
balloon catheter takes a minimum of 15-20 minutes. X-ray
fluoroscopy and contrast media are extensively used during the
guiding catheter and balloon catheter manipulations, especially
when the balloon tip is being manipulated through the inside of the
artery toward an obstructed segment which needs to be reopened by
the balloon tip. Sometimes, the majority of the procedure time and
the limits of the total allowable contrast volume are used up at
this phase of a procedure. It is clear from the medical literature
that the longer the procedure, the greater the risk of
complications during cardiac catheterization. Likewise, the larger
the volume of contrast material, the greater the chance of kidney
failure or tissue toxicity, including brain and/or liver
damage.
The size and diameter of the balloon to be used in a transluminal
angioplasty should be approximately matched to the size and native
diameter of the obstructed segment of the artery to be dilated. If
the balloon size and diameter is smaller than the native artery,
the results of balloon angioplasty are suboptimal, requiring a
second dilation with a larger-sized balloon. In some cases, the
result is a failed procedure, which may require either a second
separate angioplasty procedure (especially if too much contrast
material was already used) or bypass surgery. If the balloon is
oversized in relation to the obstructed segment of the native
vessel, the inner wall of the artery may dissect from the remainder
of the artery and may occlude the vessel completely, causing total
cessation of blood flow to the target area of the myocardium. This
complication, except in rare occasions, leads to acute myocardial
infarction and necessitates emergency bypass surgery. If the acute
occlusion leads to a large infarction, death is a possibility.
The most common balloon diameters in demand for coronary
angioplasties are 2.0 mm, 2.5 mm, 3.0 mm and 3.5 mm. The 2.0 mm and
2.5 mm balloons are used in patients with small caliber coronary
arteries or in the distal coronary branches of patients with
otherwise normal-sized coronary arteries. However, a 1.5 mm balloon
may also be desirable for certain applications. The 3.0 mm and 3.5
mm balloons are generally used in the proximal and larger native
coronary arteries. If a patient has a single obstruction in the
right or left coronary artery system, a single balloon catheter
with a matching diameter and size will be selected for the intended
dilation procedure. When the balloon is inflated inside the
obstructed segment of the native artery, the balloon should
maintain the original preshaped configuration and diameter under
the maximum allowed pressure, which is generally up to 150 psi or
more. Polymers such as PVC (polyvinylchloride) and various
derivatives of polyethylene have proved to be suitable for making
balloon catheters for coronary angioplasty. New polymer
derivatives, including variations of Mylar material, are gaining
popularity because of their high tensile strength and their
potential for making very thin-walled dilation balloons.
In single lesion dilations, the choice of a properly-sized balloon
catheter is relatively simple, although there are instances in
which the original selection of the balloon catheter is inadequate
so that a second balloon catheter is necessary to complete the
procedure successfully. However, in multi-vessel disease, balloon
catheter selection becomes compounded and complex. For example, a
patient may have three lesions in his left coronary artery, and all
three lesions may be approachable individually for successful
balloon angioplasty. But such lesions may be in vessels of
different sizes, such as a 3.0 mm lesion in the proximal portion of
the left anterior descending artery (LAD), a 2.0 mm lesion in the
distal segment of the LAD, and a 2.5 mm lesion in the superior
obtuse marginal artery. With currently available balloon catheters,
angioplasty of these three differently-sized lesions is not always
impossible, but it is cumbersome and inefficient. For each lesion,
a matching balloon catheter is exchanged and manipulated into the
target lesion under fluoroscopy with numerous contrast injections.
To do this three times in a row requires roughly three times the
procedure time, three times the contrast amount, and a minimum of
three separate balloon catheters and their accessory devices. In
light of the forecast that approximately two thirds of 450,000 to
500,000 patients in the 1990s will need multi-vessel coronary
angioplasty, it is clear that there is a need for a major advance
in balloon angioplasty that will provide more efficient and cost
effective angioplasty balloon systems specifically designed (and
suited) for multi-vessel coronary angioplasty.
In multiballoon angioplasty procedures, the smoothness and
flexibility of the distal end of the angioplasty catheter are
extremely important. Too much stiffness or rigidity in the balloon
section at the distal end of the catheter makes insertion of the
catheter more difficult. Smoothness of the catheter is also
desirable and, in a multiple balloon catheter, it will be important
to provide a smooth transition from balloon to balloon on the
outside of the catheter.
Balloon fabrication techniques heretofore employed have significant
disadvantages when it comes to multiple balloon catheters. Such
difficulties include the difficulty of providing a smooth
transition from balloon to balloon and difficulties in bonding
balloons together in a lengthwise manner. Those difficulties are
addressed by the present invention, which provides multiple balloon
catheters adapted for use in multiple vessel disease. Such
catheters have not heretofore been available and the need for an
angioplasty procedure suitable for use in multivessel disease is
readily apparent.
SUMMARY OF THE INVENTION
The present balloon angioplasty catheter invention provides an
angioplasty catheter having multiple balloons that are integrally
formed with the catheter shaft itself from a single, monolithic
piece of polymer material. This provides for an extremely smooth
transition from balloon to catheter shaft, and also minimizes the
material present in the balloon portion of the catheter, thus
providing increased flexibility for the catheter itself. The method
for making the catheters of the present invention is well adapted
for making multiple balloon catheters, and circumvents many of the
complications that would be experienced in applying conventional
balloon fabrication techniques heretofore used for single balloon
catheters to multiple balloon catheter manufacture.
The present invention is designed for compatibility with existing
and commercially available guidewires and guiding catheters,
requiring, at most, minimal modification of those existing
systems.
The balloons utilized in the present invention must meet stringent
requirements that are unique to angioplasty balloons. They are: (a)
the balloon must maintain its predetermined precise diameter and
its original configuration under high inflation pressures
(typically up to 150 psi or more) without significant or undue
stretch or deformation; (b) the material used in construction of
the balloon must have a high tensile strength and not rupture
during inflation to the prescribed high pressure; (c) the balloon
must be independently inflatable and deflatable under the external
control of the operator; (d) the cross-sectional profile of the
balloon should be low (0.90 mm to 1.20 mm or less in diameter) when
it is deflated with negative pressure so that it can pass through
the lumen of a guiding catheter and the tight and sometimes very
hard internal lumen of the stenotic segment of a target artery; and
(e) the material must be flexible as well as resilient so that the
balloon catheter can negotiate the tortuous and sometimes irregular
artery by following or advancing over a guidewire already placed in
the artery ahead of the balloon catheter.
In all of the embodiments of the present invention, radiopaque
markers may be provided on the catheter to mark the longitudinal
location of any or all of the balloons on the catheter.
For coronary angioplasty, it is preferred that none of the balloons
exceed about 40 mm in length, and most preferably none of the
balloons exceed about 30 mm in length. For peripheral angioplasty,
it is preferred that none of the balloons exceed about 100 mm in
length, and they most preferably do not exceed about 80 mm in
length. For coronary angioplasty, it is further preferred that the
maximum inflated diameter of each of the balloons does not exceed
about 4.5 mm. For peripheral angioplasty, it is preferred that the
maximum inflated diameter of each of the balloons does not exceed
about 15 mm, although larger diameters may be required for aortic
use. Finally, for valvular angioplasty, it is preferred that none
of the balloons exceed about 30 mm, preferably 25 mm, in diameter,
and that they do not exceed 65 mm, preferably 60 mm, in length.
Thus, in accordance with one aspect of the present invention, there
is provided an angioplasty catheter, comprising a catheter shaft
having a proximal end and a distal end, an angioplasty balloon on
the distal end of the catheter shaft, the balloon having a balloon
wall and a length, wherein the balloon and the distal end of the
catheter are formed from a single monolithic piece of polymer
material and wherein the balloon is eccentrically positioned with
respect to the catheter shaft, and at least two lumens in the
catheter shaft, one of the lumens in communication with the
interior of the balloon, and the other extending through the
balloon and being suitable for receiving a steerable guidewire.
In accordance with another aspect of the present invention, there
is provided an angioplasty catheter, comprising a catheter shaft
having a proximal end and a distal end with at least two lumens
extending therethrough, and an angioplasty balloon on the distal
end of the catheter shaft, wherein the balloon and the distal end
of the catheter shaft are formed from a single monolithic piece of
polymer material by sealing shut the distal end of one of the
lumens and heating the distal end of the catheter shaft, then
internally pressurizing the sealed lumen to expand at least a
portion of the distal end of the catheter shaft into the balloon,
wherein the balloon is eccentric with respect to the catheter
shaft.
In accordance with another embodiment of the present invention,
there is provided an angioplasty catheter, comprising a catheter
shaft having a proximal end and a distal end, at least two
independently inflatable and independently deflatable angioplasty
balloons at the distal end of the catheter, each balloon having a
balloon wall and having a length and a maximum inflated diameter,
wherein the balloons and the distal end of the catheter shaft are
formed from a single, monolithic piece of polymer material and
wherein the balloons are eccentrically positioned with respect to
each other. The balloons may advantageously also be eccentric with
respect to the catheter shaft. Moreover, the wall of each balloon
may be joined to either another of the balloons or to the catheter
shaft along substantially the entire length of each balloon.
It is preferred that maximum inflated diameter of each balloon is
substantially uniform over the length of the balloon when measured
together with the thickness of any overlying, uninflated
balloon.
In one preferred embodiment, the balloons comprise a first balloon
and a second balloon, and the maximum inflated diameter of the
first balloon is less than the maximum inflated diameter of the
second balloon. The first balloon may be at least partially inside
the second balloon, and preferably at least 15% but less than 85%
of the length of the first balloon is inside the second balloon. In
an alternative embodiment, the first balloon is distal of the
second balloon. The first balloon and the second balloon are
located on the same side of the catheter shaft, or on opposite
sides.
In yet another embodiment of the invention, the balloons comprise a
first balloon and the second balloon and further comprise a third
balloon on the catheter shaft. Two balloons may be on the same side
of the catheter shaft and the other balloon may be on the opposite
side of the catheter shaft; alternatively, the balloons may all be
on the same side of the catheter shaft.
In yet another embodiment of the invention, the catheter shaft
extends through the balloons, and the catheter shaft has a lumen
extending the length of the catheter shaft for receiving a
steerable guidewire.
In still another embodiment of the invention, the catheter shaft
includes at least a first lumen and a second lumen extending
through the catheter shaft, and the balloons comprise a first
balloon and a second balloon, wherein the first lumen terminates
inside the first balloon and the second lumen terminates inside the
second balloon. In this embodiment, the catheter further comprises
an axial torque guidewire extending through the first lumen and out
of the distal end of the first balloon and the catheter, wherein
the distal end of the first balloon is sealed to the guidewire. The
walls of the first balloon may be formed by expanding the walls of
the first lumen and the first balloon may be substantially coaxial
with the first lumen. Moreover, the walls of the second balloon may
be formed by expanding the walls of the second lumen and the second
balloon may be eccentric with respect to the second lumen. The
catheter may still further comprise a third balloon and the
catheter shaft may have a third lumen in communication with and
terminating inside the third balloon, wherein the third balloon is
eccentric with respect to the third lumen.
In any of the catheters disclosed herein, the walls of each balloon
may be joined to a common line on the catheter shaft along
substantially the entire length of each balloon. Alternatively, the
wall of the first balloons may be joined to the catheter shaft
along a line extending substantially the length of the first
balloon and the wall of the second balloon may be joined to the
wall of the first balloon along a line extending along the length
of the first balloon. Moreover, each balloon has a proximal end and
a distal end, and the distal end of one of the balloons may be
joined to the wall of another of the balloons.
In accordance with another aspect of the present invention, there
is provided a method for making angioplasty balloons, comprising
the steps of forming from a single piece of polymer material a
length of catheter shaft material having at least a first lumen and
a second lumen therein, each lumen having an outer wall, each lumen
having a proximal end and a distal end, sealing the distal end of
the first lumen to form a first sealed lumen, and applying pressure
to the proximal end of the first sealed lumen and heating the outer
wall thereof to expand the first sealed lumen inside a first die to
expand the outer wall of the first sealed lumen to form a first
balloon therefrom having dimensions determined by the dimensions of
the interior of the die. The method may further comprise the steps
of sealing the distal end of the second lumen to form a second
sealed lumen, applying pressure to the proximal end of the second
sealed lumen and heating the outer wall thereof to expand the
second sealed lumen inside a second die to form a second balloon
therefrom having dimensions determined by the dimensions of the
interior of the second die, wherein the first balloon and the
second balloon are eccentric with respect to each other. The sealed
end of the first lumen may be located distally of the sealed end of
the second lumen so that the distal end of the first balloon is
located distally of the distal end of the second balloon. In one
embodiment, the outer wall of the first lumen is located inside the
outer wall of the second lumen. In another embodiment, the first
balloon and the second balloon are located on opposite sides of the
catheter. The forming step may advantageously be a molding step or
an extrusion step. When the forming step is an extrusion step, the
method may further comprise the step of shortening the second lumen
prior to sealing the distal end thereof by removing a length of the
outer wall of the second lumen at the distal-most end of the second
lumen so that the distal end of the second lumen is located
proximally of the distal end of the first lumen.
In one embodiment of the method, the sealing step for the second
lumen comprises bonding the outer wall of the second lumen at the
distal end thereof to the outer wall of the first lumen.
In each embodiment of the method, the catheter shaft material may
further have a third lumen therein, and the method may further
comprise the steps of sealing the distal end of the third lumen to
form a third sealed lumen, and applying pressure to the proximal
end of the third sealed lumen and heating the outer wall thereof to
expand the outer wall of the third sealed lumen inside a die to
form a third balloon therefrom having dimensions determined by the
dimensions of the interior of the die.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of the distal end of a dual-balloon
steerable guidewire limacon geometry angioplasty catheter having
balloons on the same side of the guidewire lumen showing the
balloons and connecting lumens in longitudinal section and the
guidewire lumen in partial cross section.
FIG. 2 is a perspective view of the distal end of the catheter of
FIG. 1, partially in cross section.
FIG. 3 is a cross section of the catheter of FIG. 2, taken along
the line 3--3.
FIG. 4 is a cross section of the catheter of FIG. 2, taken along
the line 4--4.
FIG. 5 is a cross section of the catheter of FIG. 2, taken along
the line 5--5.
FIG. 6 is a cross section of the catheter of FIG. 2, taken along
the line 6--6.
FIG. 7 is a side elevation of the distal end of a steerable
guidewire dual balloon catheter of the present invention having
balloons on opposite sides of the catheter shaft, with balloon
lumens and balloons shown in longitudinal section and with the
guidewire lumen shown in partial cross section.
FIG. 8 is a cross section of the catheter of FIG. 7, taken along
the line 8--8.
FIG. 9 is a cross section of the catheter of FIG. 7, taken along
the line 9--9.
FIG. 10 is a cross section of the catheter of FIG. 7, taken along
the line 10--10.
FIG. 11 is a side elevation of the distal end of a triple balloon
steerable guidewire catheter of the present invention, having
integrally-formed balloons on opposite sides of the guidewire
lumen, with balloons shown in longitudinal section and with the
guidewire lumen and the distal balloon lumen shown in partial
section.
FIG. 12 is a cross section of the catheter of FIG. 11, taken along
the line 12--12.
FIG. 13 is a cross section of the catheter of FIG. 11, taken along
the line 13--13.
FIG. 14 is a cross section of the catheter of FIG. 11, taken along
the line 14--14.
FIG. 15 is a side elevation of a triple balloon steerable guidewire
catheter of the present invention, having two overlapping balloons
on one side of the guidewire lumen, and another balloon on the
opposite side of the guidewire lumen, with the balloon lumens and
balloons shown in longitudinal section.
FIG. 16 is a cross section of the catheter of FIG. 15, taken along
the line 16--16.
FIG. 17 is a cross section of the catheter of FIG. 15, taken along
the line 17--17.
FIG. 18 is a cross section of the catheter of FIG. 15, taken along
the line 18--18.
FIG. 19 is a cross section of the catheter of FIG. 15, taken along
the line 19--19.
FIG. 20 is a side elevation of the distal end of an axial torque
guidewire overlapping double balloon catheter of the present
invention, with the balloons and the catheter shaft shown in
longitudinal section.
FIG. 21 is a cross section of the catheter of FIG. 20, taken along
the line 21--21.
FIG. 22 is a cross section of the catheter of FIG. 20, taken along
the line 22--22.
FIG. 23 is a cross section of the catheter of FIG. 20, taken along
the line 23--23.
FIG. 24 is a side elevation of the distal end of a tandem dual
balloon axial torque guidewire catheter of the present invention,
showing the catheter shaft and balloons in longitudinal
section.
FIG. 25 is a cross section of the catheter of FIG. 24, taken along
the line 25--25.
FIG. 26 is a cross section of the catheter of FIG. 24, taken along
the line 26--26.
FIG. 27 is a side elevation of a triple balloon axial torque
guidewire catheter of the present invention, with the balloons and
catheter shaft shown in longitudinal section.
FIG. 28 is a cross section of the catheter of FIG. 27, taken along
the line 28--28.
FIG. 29 is a cross section of the catheter of FIG. 27, taken along
the line 29--29.
FIG. 30 is a cross section of the catheter of FIG. 27, taken along
the line 30--30.
FIG. 31 is a side elevation of a portion of the balloon segment of
a catheter of the type illustrated in FIG. 2, showing one
embodiment of a joint between two balloons.
FIG. 32 is a side elevation of a portion of the balloon segment of
a catheter of the type illustrated in FIG. 2, showing another
embodiment of a joint between two balloons.
FIG. 33 is a side elevation of a portion of the balloon segment of
a catheter of the type illustrated in FIG. 2, showing yet another
embodiment of a joint between two balloons.
FIG. 34 is a diagram of the left coronary artery system.
DETAILED DESCRIPTION OF THE INVENTION
The angioplasty catheters of the present invention fall into two
broad, general categories: steerable guidewire type catheters and
axial torque guidewire-type catheters. Both steerable guidewire
catheters and axial torque guidewire catheters are known in the
art. Briefly, a steerable guidewire-type catheter has a guidewire
lumen extending the entire length of the catheter, from the
proximal end to the distal end thereof, and the guidewire lumen
extends through or past all of the balloons. A guidewire can be
threaded through the lumen and is rotatable through the lumen. An
axial torque guidewire-type catheter, on the other hand, has a
guidewire that extends through a lumen that terminates inside the
distal-most balloon, and the guidewire extends out from the distal
end of the distal-most balloon. The distal-most end of the balloon
is bonded directly to the guidewire so that rotation of the
proximal end of the guidewire about its axis rotates the guidewire
tip to permit selection of a target vessel.
In general, the balloons of the present invention share a number of
characteristics in common with conventional angioplasty balloons.
These characteristics differentiate angioplasty balloons from other
types of known catheter balloons. Angioplasty balloons are
generally cylindrical and have a predetermined maximum inflated
diameter that remains more or less constant over the range of
working pressures to which the balloon is subjected. Modern balloon
materials can be inflated with pressures of at least 100 psi,
preferably at least 150 psi, and often 200 psi. The balloon wall is
not resilient, elastic material, but instead is folded against the
catheter shaft in its deflated state and, upon inflation, assumes a
predetermined shape. Even when inflation pressures reach the high
values discussed herein, only a minor amount of stretching, if any,
occurs. The hard, non-elastic balloon, when inflated, has the
ability to compress sclerotic lesions or stretch the narrowed
segments in order to increase blood flow through a diseased blood
vessel.
The angioplasty catheters of the present invention are suitable for
coronary angioplasty, peripheral angioplasty, and valvular
angioplasty. The angioplasty balloons may be provided in different
diameters and lengths, depending on the intended use of the
catheter. Balloon catheter shafts of size French 4.0 or less are
preferred. For coronary angioplasty, balloon diameters of from
about 1.0 mm to about 4.0 mm and lengths from about 7 mm to about
30 mm are preferred. For peripheral vascular angioplasty and valve
angioplasty, the balloons may have diameters between about 3.0 mm
and about 20 mm, with lengths between about 25 mm and about 60
mm.
Any of a number of materials may be used to make the balloon
catheters of the present invention. At least the distal end of the
catheter and the balloons are preferably formed from high-strength
thermoplastic material, which may be the same as conventional
angioplasty balloon materials or may be other, advanced
thermoplastic materials. Balloon materials that have been used or
are now in use include polyvinylchloride, polyethylene,
polyethylene terephthalate (PET) mylar brand polyester material
(made by du Pont). Other suitable film-forming materials capable of
withstanding pressures of 100 psi, preferably 150 psi or 200 psi,
without bursting or significant stretching, may also be used to
form the distal end of the catheter and the angioplasty
balloons.
The catheters of the present invention are typified by the dual
balloon catheter illustrated in FIGS. 1 and 2. To the extent that
the catheters retain common or comparable elements from Figure to
Figure, the same numbering will be applied to such elements, which
will not always be separately explained for each Figure.
The catheters of the present invention are referred to as having
"limacon" geometry because of the resemblance of the cross section
of the catheter to a limacon. It will be understood, however, that
the catheters of the present invention are not required to exhibit
true limacon geometry in cross section.
I.
Steerable Guidewire-Type Limacon Geometry Catheters
With respect to FIGS. 1 and 2, a catheter 40 has at least one
balloon, the first balloon 42 at the distal end 44 of the catheter
40. The catheter 40 also has a proximal end 46 which is indicated
at the far left-hand side of FIG. 2; however, it will be understood
that the proximal end 46 of the catheter 40 is the end at the
extreme opposite end of the catheter 40 from the distal end 44, and
that the true proximal end 46 is not shown in FIG. 2. Rather, FIG.
2 illustrates only the distal balloon-bearing portion of the
catheter 40, and the reference numeral 46 is provided only for
purposes of indicating the proximal direction.
The catheter 40 also has a catheter shaft 50 on which a first
balloon 42 is formed. As used herein, the catheter shaft 50 shall
refer to the lumens and their walls in an expanded state. The
catheter shaft 50 shall not be considered to include outer walls of
lumens which have been expanded into balloons. The first balloon 42
has a first balloon wall 52. A first lumen 54 having an outer wall
56 extends from the proximal end 46 of the catheter 40 to the
interior of the first balloon 42, providing a fluid passageway
between the proximal end 46 of the catheter 40 and the interior of
the first balloon 42.
The catheter shaft 50 is also provided with a guidewire lumen 60
through which a steerable guidewire may be passed. The guidewire
lumen has an outer wall 68 and extends from the proximal end 46 of
the catheter shaft 50 to the distal end 44 of the catheter 40, and
is large enough to receive a conventional steerable guidewire and
to further permit monitoring of blood pressure through the
guidewire lumen 60. The guidewire lumen 60 and any guidewire placed
therethrough extend beyond the distal-most end of any of the
balloons, such as first balloon 52, on the catheter 40. The
guidewire lumen 60 of the catheter 40 preferably has an inner
diameter of about 0.014 to about 0.016 inches, just large enough to
accommodate a 0.012 or 0.014 inch conventional steerable guidewire
inside and to monitor distal pressure through the lumen. The
outside diameter of the catheter shaft 50 at the proximal end 46 of
the catheter 40 should be size French 4.0 or less. In all of the
steerable guidewire catheters of the present invention, holes
communicating with the guidewire lumen 60 may be provided just
proximally of the balloons to permit blood flow through the
guidewire lumen 60 and past the balloons 42, 62, to maintain
coronary perfusion during balloon inflation.
A second balloon 62 having a wall 64 is also provided on the
catheter shaft 50. A second lumen 66 having an outer wall 70
extends through the catheter shaft from the proximal end 46 thereof
to the interior of the second balloon 62 to provide fluid
communication between the proximal end 46 of the catheter 40 and
the second balloon 62.
At least the portion of the catheter 40 illustrated in FIG. 2, from
a point just proximally of the balloons 42, 62, including the
catheter shaft 50, the walls 56, 70 of the lumens 54, 66, and the
walls 52, 64 of the balloons 42, 62, is all formed from a single,
monolithic piece of polymer material. Thus, the outer wall 56 of
the first lumen 54 has been enlarged and stretched to form the wall
52 of the first balloon 42. Similarly, the outer wall 70 of the
second lumen 66 has been enlarged and stretched to form the wall 64
of the second balloon 62. It should be understood that the
thickness of the balloon walls 52, 64 is generally between about
0.01 mm and 0.10 mm, depending on the strength and flexibility of
the material from which the balloons 42, 62 are formed. This
thickness is greatly exaggerated in all of the figures for purposes
of illustration only. Moreover, the thickness of the outer walls
56, 70 of the lumens 54, 56 is substantially greater than the
thickness of the balloon walls 52, 64. The outer walls 56, 70 of
the lumens 54, 66 are rigid enough to maintain their dimensions
when negative pressure is applied to the proximal end of the lumens
54, 66. In contrast, the very thin balloon walls 52, 64 are
flexible and readily collapse when negative pressure is applied to
the appropriate lumen for each balloon.
The guidewire lumen 60 has an outer wall 68. As illustrated in FIG.
3, each of the outer walls 56, 68, 70 of the lumens 54, 60, 66
converge to a common point or line into a common wall 72. Thus, the
common wall 72 is a convergence point for outer lumen walls 56, 68,
70. The lumen walls 56, 68, 70, 72 in radial cross section, as
shown in FIG. 3, are arranged as eccentric circles, one within
another, longitudinally joined together at the common lumen wall
72. The common lumen wall 72 is a line running the length of the
catheter shaft 50.
The balloon arrangement in the dual balloon limacon geometry
catheter 40 of FIGS. 1 and 2 is a partial overlap design. That is,
the first balloon 42 is partially inside the second balloon 62. The
distal end 74 of the first balloon 42 is joined to the outer wall
68 of the guidewire lumen 60. The distal end 76 of the second
balloon 62 is joined semicircularly to the underlying wall 52 of
the first balloon 42. The joints 77, 79 between the distal ends 74,
76 of the first and second balloons 42, 62 and the underlying
structure, are formed using any suitable balloon joint bonding
process, such as heat bonding, vulcanization bonding, solvent
bonding, ultrasonic welding, laser welding, and glue bonding. These
balloon joints are semicircular around the catheter shaft; thus,
substantially the entire distal ends 74, 76 of the first and second
balloons 42, 62 are closed. The joint itself in all of the balloon
designs may lie in a plane normal to the axis or length of the
catheter shaft 50, or it may preferably lie in a plane at an acute
angle to the length of the catheter shaft 50.
The first balloon 42 may be completely inside the second balloon
62; however, it is preferred that the first balloon 42 be only
partially inside the second balloon 62. In a preferred embodiment,
at least 15% of the length of the first balloon 42 is inside the
second balloon 52, but less than 85% of the length of the first
balloon 42 is inside the second balloon 62. It should be
understood, however, that the design of FIG. 2 may be modified to
provide a tandem dual-balloon limacon geometry catheter, wherein
the entire first balloon 42 is located distally of the second
balloon 62. In the tandem design, the first balloon 42 is
completely outside the second balloon 62.
Under ordinary conditions of use, when one of the balloons 42, 62
is inflated, the other balloon will be deflated. (Both balloons 42,
62 are shown in the inflated configuration simply for purposes of
illustration.) Although the wall 64 of the outer balloon 62 is very
thin, it is nevertheless tangible. In a preferred embodiment of the
present invention, in order for the effective maximum inflated
working diameter of the first balloon 42 to be uniform along
substantially its entire length, the diameter of the portion of the
first balloon 42 that is inside the second balloon 62 is slightly
less than the diameter of the portion of the first balloon 42 that
is outside the second balloon 62, with the difference in diameters
between the two portions of the balloon 42 being approximately
equal to the thickness of the overlying, uninflated second balloon
62. In this way, the maximum inflated effective working diameter of
the first balloon 42, together with any overlying uninflated
balloon walls, is substantially uniform along the entire length of
the first balloon 42.
In one alternative embodiment of the present invention which may be
applied to any of the designs falling within the scope of the
present invention, radiopaque markers 78 may be provided on the
catheter shaft 50 so the location of the catheter may be
radiographically monitored.
The balloon construction may be more fully understood by comparison
of the cross-sectional FIGS. 3-6. In the cross section of the
second balloon 62 and the catheter shaft 50 illustrated in FIG. 4,
the first lumen 54, its outer wall 56, the guidewire lumen 60, its
outer wall 68, and the common wall 72 are substantially the same as
in FIG. 3. However, the outer wall 70 of the second lumen 66 shown
in FIG. 3, has, in FIG. 4, become the wall 64 of the second balloon
62.
In FIG. 5, a cross section through the catheter shaft 50 and both
the first balloon 42 and the second balloon 62, the common wall 72,
the guidewire lumen 60, and its outer wall 68 are substantially the
same as in FIGS. 3 and 4. However, the outer wall 56 of the first
lumen 54 in FIGS. 3 and 4 has been expanded to form the wall 52 of
the first balloon 42, and the outer wall 70 of the second lumen 66
in FIG. 3 has become the wall 64 of the second balloon 62.
In FIG. 6, which is a cross section through only the first balloon
42 and the catheter shaft 50, taken distally of the second balloon
62, only the guidewire lumen 60, its outer wall 68, and the common
wall 72 remain the same as illustrated in FIG. 3. The wall 52 of
the first balloon 42 converges with the outer wall 68 of the
guidewire lumen 60 at the common wall 72, which common wall 72 runs
the entire length of the catheter 40. The wall 64 of the second
balloon 62 (and/or the wall 70 of the second lumen from which it
was formed) has been removed from the distal-most end of the
catheter 40, and is not present in FIG. 6, the second balloon 62
having terminated proximally of the line 6--6.
The balloons 42, 62 in FIGS. 1 and 2 are eccentric with respect to
each other and with respect to the catheter shaft 50 and the
guidewire lumen 60. However, both the first balloon 42 and the
second balloon 62 are located on the same side of the catheter
shaft 50.
The first balloon 42 has a maximum inflated diameter that is less
than that of the second balloon 62. The maximum inflated diameter
of the first balloon 42 is preferably about 1.5, 2.0, 2.5, or 3.0
mm. The maximum inflated diameter of the larger, second balloon 62
is preferably 2.5 mm, 3.0 mm, 3.5 mm or 4.0 mm. The lengths of each
of the balloons may advantageously be between about 15 mm and about
40 mm, preferably about 20 mm to about 25 mm.
Another dual balloon limacon-geometry steerable guidewire
angioplasty catheter is illustrated in FIG. 7. The catheter 40 has
a first balloon 42 on one side of the catheter shaft 50, and a
second balloon 62 on the opposite side of the catheter shaft 50. A
guidewire lumen 60 having an outer wall 68 on either side of common
wall 72 runs the length of the catheter 40 and completely through
the two balloons 42, 62.
The catheter of FIG. 7 differs from the catheters of FIGS. 1 and 2
because the balloons 42, 62 are on opposite sides of the catheter
shaft 50 and the guidewire lumen 60.
A first lumen 54 and a second lumen 66 extend from the proximal end
46 of the catheter 40 into the interior, respectively, of the first
balloon 42 and the second balloon 62 for independent inflation and
deflation of the balloons 42, 62.
The outer wall 56 of the first lumen 54 becomes the wall 52 of the
first balloon 42, and the outer wall 70 of the second lumen 66
becomes the wall 64 of the second balloon 62.
In FIG. 8, which illustrates a cross section of the catheter shaft
50 of the catheter of FIG. 7 taken proximally of the balloons 42,
62, it can be seen that the outer wall 56 of the first lumen 54
merges with the outer walls 68 to form two common walls 72. The
outer wall 70 of the second lumen 66 merges with and is connected
to the outer wall 56 of the first lumen 54 at a point adjacent to
the common walls 72.
In FIG. 9, a cross section through both the first balloon 42 and
the second balloon 62, together with the guidewire lumen 60, the
outer walls 56, 70 of the first and second lumens 54, 66 have
become the walls 52, 64 of the first and second balloons 42, 62.
Only the guidewire lumen 60, its outer wall 68, and the common wall
72 remain the same as in FIG. 8.
In FIG. 10, a cross section taken through the first balloon 42
distally of the distal end 76 of the first balloon 72, only the
wall 52 of the first balloon 42 and the central lumen 60 and its
walls 68, 72 remain the same as in FIG. 9.
The diameters of the first and second balloons 42, 62 in FIG. 7 may
advantageously be about the same as the diameters of the first and
second balloons 42, 62 in the catheter illustrated in FIG. 2.
However, in this design, the first balloon 42 is longer than the
second balloon 62. Thus, although the proximal ends of the first
and second balloons 42, 62 are at substantially the same point
along the length of the catheter 40, the distal end 76 of the
second balloon 62 is located proximally of the distal end 74 of the
first balloon 42. The length of the first balloon 42 is preferably
25-45 mm, most preferably about 30 mm, and the length of the second
balloon 62 is preferably 15-30 mm, preferably about 20 mm. Thus,
the length of the first balloon 42 is greater than the length of
the second balloon 62 by about 10 mm.
When the second balloon 62 is deflated and the first balloon 42 is
inflated, the maximum inflated diameter of the first balloon 42
distally of the distal end 76 of the second balloon 62 is slightly
greater than the maximum inflated diameter of the first balloon 42
proximatelly of the distal end 76 of the second balloon 62 by an
amount substantially equal to the thickness of the deflated balloon
62. In this way, the effective maximum inflated diameter of the
first balloon 42 is substantially uniform along the entire length
of the first balloon 42, when taken together with the thickness of
the overlying deflated second balloon 62.
The catheter illustrated in FIG. 7 has three effective working
diameters. The first is the diameter of the first balloon 42, the
second is the maximum inflated diameter of the second balloon 62,
and the third effective diameter of the catheter of FIG. 7 is
achieved by inflating both the first balloon 42 and the second
balloon 62.
The catheter of FIG. 11 is a steerable guidewire catheter that has
a first balloon 42 and a second balloon 62 generally as described
in connection with FIG. 7. However, unlike the catheter of FIG. 7,
the catheter of FIG. 11 includes a separate, non-unitary third
balloon 80 located distally of the first balloon 42 and the second
balloon 62. The separate third balloon 80 is separately formed and
connected to the catheter shaft 50; it is not formed from the same
monolithic piece of polymer material as are the first and second
balloons 42, 62 and the catheter shaft 50.
In addition to the first lumen 54, the second lumen 66, and the
guidewire lumen 60 described in connection with FIG. 7 and FIG. 2,
the catheter of FIG. 11 has a third lumen 82 extending from the
proximal end 46 of the catheter 40 to the interior of the third
balloon 80 for independently inflating and deflating the third
balloon 80.
In the catheter of FIG. 11, the first, second, and third balloons
42, 62, 80 are eccentric with respect to each other and the first
and second balloons 42, 62 are eccentric with respect to the
catheter shaft 50. Although in FIG. 11 the proximal end of the
first balloon 42 is located at the same point as the proximal end
of the second balloon 62, it should be understood that the proximal
end of the first balloon 42 may instead be located distally of the
proximal end of the second balloon 62.
The third balloon 80 is substantially coaxial with the catheter
shaft 50 and is made from a tube of suitable balloon material which
may be the same as or different from the material from which the
first balloon 42 and the second balloon 62 are made. The third
balloon 80 is bonded to the catheter shaft 50 by any conventional
means, such as heat bonding, RF bonding, laser bonding, solvent
welding, adhesive bonding, heat-shrink bonding, or other suitable
technique.
The maximum inflated diameter of the third balloon 80 is preferably
less than the maximum inflated diameter of the first balloon 42 and
the second balloon 62. For coronary angioplasty, the third balloon
80 may have a maximum inflated diameter of about 2.0 mm and may be
about 12-25 mm in length, preferably about 17 mm, the first balloon
42 may be from about 20 to about 30 mm in length, preferably about
25 mm, with a maximum inflated diameter of about 2.5 mm, and the
second balloon 62 may be about 12-20 mm in length, preferably about
17 mm, with a maximum inflated diameter of about 3.0 mm. In another
embodiment of this same catheter, the aforementioned maximum
inflated diameters may each be increased or decreased by about 0.5
mm.
As shown in FIG. 12, a cross section through both the first balloon
42, the second balloon 62, and the catheter shaft 50, appears
substantially the same as FIG. 9, except that a second lumen 82 is
present. FIG. 13 similarly corresponds to FIG. 10, differing from
FIG. 10 by the inclusion of the third lumen 82.
In FIG. 14, a cross section through the third balloon 80, only the
central lumen 60, the outer wall 68 thereof, and the third balloon
80 are present.
Yet another catheter according to the present invention is
illustrated in FIG. 15. This catheter is a triple balloon steerable
guidewire catheter in which all three balloons are formed from the
same monolithic piece of polymer material.
The catheter of FIG. 15 has a first balloon 42 and a second balloon
62, with the first balloon 42 partially inside the second balloon
42. The detailed description provided in connection with the
catheter disclosed in FIG. 2 will not be repeated with respect to
FIG. 15; only the structure added to the catheter of FIG. 2 will be
emphasized.
In addition to the first balloon 42 and the second balloon 62
illustrated in FIG. 2, the catheter of FIG. 15 has a unitary third
balloon 84 on the opposite side of the catheter from said first and
second balloons 42, 62. A third lumen 82 is provided in the
catheter shaft 50 in fluid communication with the interior of the
third balloon 84. The third lumen 84 has an outer wall 86 which, as
illustrated in cross section FIG. 16, is attached to the outer wall
70 of the third lumen 66 at two wall-to-wall junctions 90. The
wall-to-wall junctions 90 run from the proximal end 46 of the
catheter 40 to the distal end 92 of the third balloon 84.
The proximal ends of the second balloon 62 and the third balloon 84
are at roughly the same point along the length of the catheter
shaft 50. The distal ends 76, 92 of the second balloon 62 and the
third balloon 84 may also be located at roughly the same point
along the length of the catheter shaft 50; however, a slightly
offset relationship as illustrated in FIG. 15 is preferred. The
catheter will generally be stiffer and/or bulkier at the distal end
of a balloon because of the joint located at that point. Therefore,
a smoother more flexible catheter results if the distal ends 76, 92
are slightly (or greatly) offset, rather than terminating at
exactly the same point along the length of the catheters. In FIG.
15, two balloons 42, 62 are on one side of the catheter shaft 50
and one balloon 84 is on the other side of the catheter shaft
50.
FIG. 17 differs from FIG. 16 in that the outer walls 70, 86 of the
second and third lumens 66, 82 have been expanded to form the
second balloon 62 and the third balloon 84. As were the lumen walls
70, 86 from which they were formed, the second and third balloons
62, 84 are joined together along their length at the wall-to-wall
junctions 90, which extend to the distal ends 76, 92 of those
balloons 62, 84.
FIG. 18, a cross section through all three balloons 42, 62, 84,
differs from FIG. 17 only in that the outer wall 56 of the first
lumen 54 has become the wall 52 of the first balloon 42.
In FIG. 19, a cross section through only the first balloon 42, the
catheter at that point comprises only the wall 52 of the first
balloon 42 and the central lumen 60 with its walls 68 and 72.
The first balloon 42, the second balloon 62, and the third balloon
84 may advantageously be approximately the same length, preferably
between about 12 mm and about 25 mm, more preferably about 17 mm,
with diameters, respectively, of 2.0 mm, 2.5 mm and 3.0 mm. In
other embodiments of the invention, the respective diameters of the
three balloons 42, 62, 84 may be increased or decreased 0.5 mm.
II.
Axial Torque-Type Limacon Geometry Catheters
FIG. 20 illustrates an axial torque-type limacon geometry multiple
balloon catheter. In the illustrated dual balloon model, the
catheter 40 has a first balloon 42 near the distal end 44 of the
catheter 40. The catheter shaft 50 extends only to the proximal end
of the first balloon 42. A first lumen 54 extends from the proximal
end 46 of the catheter 40 to the interior of the first balloon 42
to provide for independent inflation and deflation of the first
balloon 42.
A second balloon 62 may be provided on one side of the catheter
shaft 50 and the first balloon 42. The second balloon 64 is
connected to the proximal end 46 of the catheter 40 by a second
lumen 66 running from the proximal end 46 of the catheter to the
interior of the second balloon 62. The distal end 76 of the second
balloon 62 is joined to the wall 52 of the first balloon 42.
An axial torque steel wire 94 runs the length of the catheter 40
from the proximal end 46 to the distal end 44 thereof. The axial
torque steel wire 94 is preferably tapered from a proximal diameter
of about 0.016 inches to a diameter at the distal tip thereof of
about 0.008 inches. The distal end 74 of the first balloon 42 is
bonded directly to the axial torque wire 94 by conventional bonding
means, such as adhesive bonding, heat bonding, heat-shrink bonding,
or other technique. The tip of the torque wire is welded to a short
guidewire at the distal end of the catheter 40. No guidewire lumen
60 separate from the first lumen 54 is provided in this design.
Because an axial torque limacon catheter having dual balloons may
be made with as few as two lumens, the catheter shaft 50 may be of
relatively small diameter. Moreover, because there is no catheter
shaft running through the first balloon 42, the balloon can
collapse against the axial torque wire to provide a catheter with
an extremely low profile and good flexibility at the distal end
thereof. Thus, because the collapsed balloons are not filled with
the catheter shaft 50, they can collapse to the fullest possible
degree.
The first balloon 42 is at least partially inside the second
balloon 62. The lengths of the respective balloons are a matter of
choice. Thus, if desired, the second balloon 62 may be as long as
or longer than the first balloon 42, and may extend substantially
to the distal end 74 of the first balloon 42. However, as shown in
FIG. 20, it is preferred that the first balloon 42 extend distally
from the distal end 76 of the second balloon 62 for at least 15% of
the length of the first balloon 42, and preferably for at least
about 30% or 40% of the length of the first balloon 42. The first
balloon 42 is substantially coaxial with the catheter shaft 50 (or
at least the first lumen 54 thereof), and the second balloon 62 is
eccentric with respect to the catheter shaft 50 and the guidewire
94. Moreover, the first balloon 42 and the second balloon 62 are
eccentric with respect to each other.
As shown in FIG. 21, a cross section of the catheter shaft
proximally of the balloons 42, 62, the first lumen 54 has an outer
wall 56. The guidewire 94 extends through the first lumen 54. The
second lumen 66 has an outer wall 70 on the same side of the
guidewire 94 as the outer wall 56 of the first lumen 54. The outer
walls 56, 70 of the first and second lumens 54, 66 converge
together and are joined at a common lumen wall 72 running from the
balloons 42, 62 to the proximal end 46 of the catheter 40.
FIG. 22 is a cross section through both the first and second
balloons 42, 62. In this figure, the outer wall 56 of the first
lumen 54 has been expanded to form the wall 52 of the first balloon
42. The common lumen wall 72 has also become part of the wall 52 of
the first balloon 42. The outer wall 70 of the second lumen 66 has
become the wall 64 of the second balloon 62. The first balloon 42
and the second balloon 62 are joined together at at least one
wall-to-wall junction 90. Two wall-to-wall junctions 90 are
illustrated in FIG. 2.
In FIG. 23, only the wall 52 of the first balloon 42 remains, with
the guidewire 94 extending therethrough.
The catheter of FIG. 24 is similar to the catheter of FIG. 20 in
that it is a dual balloon axial torque limacon geometry angioplasty
catheter. However, instead of overlapping, the first balloon 42 and
the second balloon 62 are arranged on the catheter shaft 50 in
tandem relationship. That is, the first balloon 42 is located
distally of the distal end 76 of the second balloon 62. As in the
catheter of FIG. 20, the second balloon 42 and the first balloon 62
are eccentric with relation to each other, the second balloon 62 is
eccentric with respect to the catheter shaft 50, and the first
balloon 42 is generally coaxial with the guidewire 94, the first
lumen 54, and the catheter shaft 50.
In the cross section of FIG. 25, the outer wall 70 of the second
lumen 66 has become the wall 64 of the balloon 62, while the
unexpanded outer wall 56 of the first lumen 54 is substantially
inside the second balloon 62. The wall 64 of the second balloon 62
is joined to the outer wall 56 of the first lumen 54 at the common
lumen wall 72. FIG. 26 is identical to FIG. 23 and will not be
separately described.
The lengths of the first balloon 42 and the second balloon 62 may
be similar, and are preferably in the range of from about 12 mm to
about 25 mm for coronary angioplasty. The diameters of the first
and second balloons 42, 62 may respectively be about 2.0 mm and
about 2.5 mm, although in alternative embodiments, they may be
increased or decreased by about 0.5 mm.
A triple balloon axial torque guidewire limacon geometry
angioplasty catheter is illustrated in FIG. 27. This embodiment has
a first balloon 42 and a second balloon 62 in tandem relationship
in much the same manner as described in connection with FIG. 21.
However, a third balloon 84 is provided on the opposite side of the
catheter shaft 50 from the second balloon 62 in much the same
manner as was described in connection with FIG. 15. The proximal
ends of the second balloon 62 and the third balloon 84 are located
at roughly the same point along the length of the catheter shaft
50; however, the distal end 92 of the third balloon 84 is
preferably located proximally of the distal end 76 of the second
balloon 62. The wall 64 of the second balloon 62 and the wall 88 of
the third balloon 84 are joined together at wall-to-wall junctions
90 running lengthwise for the length of the third balloon 84.
As illustrated in FIG. 29, a cross section taken through the second
balloon 62 between the third balloon 84 and the first balloon 42,
the wall 64 of the second balloon 62 surrounds the outer wall 56 of
the first lumen 54 with the axial torque guidewire 94 running
through the first lumen 54. The wall 64 of the second balloon 62
and the outer wall 56 of the first lumen 54 are joined together at
a common wall 72.
FIG. 30, a cross section through the first balloon, is the same as
FIGS. 26 and 23 and will not be separately explained.
The diameter of the distal first balloon 42 is preferably smaller
than the diameter of the second balloon 62, which is in turn
preferably smaller than the diameter of the third balloon 84. The
first and third balloons 42, 84 may be approximately the same
length, in the range of from about 10 mm to about 20 mm, and the
second balloon 62 may be longer, in the range of from about 20 mm
to about 30 mm. The diameters of the balloons 42, 62, 84 for
coronary angioplasty may respectively be 2.0 mm, 2.5 mm and 3.0 mm.
These diameters may each be increased or decreased about 0.5 mm in
alternative embodiments.
FIGS. 31-33 illustrate various types of joints that may be formed
between the distal end of a balloon and the underlying structure.
Although the illustrated joints 79 are between the distal end 76 of
a second balloon 62 and an underlying first balloon 42, it should
be understood that these joints may represent the joint between any
distal end of a balloon and the underlying structure, whether
another balloon or the catheter shaft 50.
In FIG. 31, the joint 79 at the distal end 76 of the second balloon
42 is not in a plane perpendicular to the length of the catheter
shaft 50, but instead lies in a plane tilted at an acute angle with
respect to the length of the catheter shaft 50. This permits
smoother and easier passage of the joint 79 through narrowed or
tortuous portions or restricted segments of a vessel.
In FIG. 32, the joint 79 describes a wavy or sawtooth line. This
type of joint is desirable for the reasons discussed in connection
with FIG. 31.
The joint 79 illustrated in FIG. 33 is slanted at an acute angle
with respect to the length of the catheter shaft 50, but it is
slanted in the direction opposite the direction of the joint in
FIG. 31. As shown in phantom in FIG. 33, the joint 79 on the side
of the catheter opposite the illustrated side may slant in a
direction opposite the direction of the joint 79 on the illustrated
side. Alternatively, it may slant in the same direction on both
sides.
Although specific embodiments have been described herein, it will
be understood that the various balloon structures disclosed may be
combined in a large variety of ways, all of which are considered to
be within the scope of the present invention. Additional balloons
may be added, to provide quadruple or other multiple balloon
catheters. Other lumen arrangements may be used. Moreover, the
balloon diameters and lengths disclosed in connection with each of
the specific illustrated embodiments are preferred coronary
angioplasty dimensions. For peripheral and valvular angioplasty,
balloon diameters preferably range from about 4 mm to about 10 mm
and balloon lengths range from about 30 mm to about 100 mm.
Appropriate modifications for such angioplasty are within the scope
of the present invention.
III.
Limacon Balloon Manufacturing Method
Unlike prior art balloon designs, which contemplate separate
extrusion of the catheter shaft and the balloon material, with
subsequent attachment of the balloons to the catheter shaft, the
present invention permits the balloons to be formed from the
catheter shaft material itself, eliminating many of the joints and
failure points found in prior art angioplasty catheters and
simplifying the fabrication of multiple balloon catheters.
Moreover, the fabrication technique is adapted for the manufacture
of angioplasty balloon catheters having balloons eccentrically
positioned with respect to each other. Thus, if each balloon is
considered to have an axis running generally through the middle
thereof, the axes of the various balloons will not coincide.
In accordance with the method of the present invention, at least
the distal-most end of the catheter is formed from a single,
unitary, monolithic piece of polymer material. Preferably, the
entire catheter, from proximal end to distal end, is formed from
such a single piece of polymer material. The balloons are formed by
expanding out the walls of individual lumens running through the
catheter shaft at the distal end of the catheter.
After selecting a suitable thermoplastic polymer, the catheter
shaft, complete with lumens (or at least the distal-most end of the
catheter shaft) is formed by molding or by extrusion. Extrusion
processes are preferred, because extrusion is a continuous process
and may be used to form long lengths of catheter shaft material
which may be cut into the appropriate length for individual
catheters. The advantage of molding processes, on the other hand,
are that they provide the prospect for combining all sealing or
bonding steps into a single molding step, except for possibly the
step of sealing a length of catheter shaft material to the molded
distal end.
Molded pieces may be directly blown to form balloons. Extruded
pieces, on the other hand, require some additional preparation. The
extruded piece has a plurality of lumens therethrough having
appropriate geometries, e.g., geometries as shown in FIGS. 3, 8, 16
or 21, or variations and adaptations of those geometries suitable
for making other balloon configurations falling within the scope of
the present invention. In each of the designs, the outer walls of
the lumens may be thinner than the common lumen walls to provide
for adequate thinning when the balloons are blown therefrom.
Moreover, any desired portion of the catheter shaft may be thinned
and/or elongated by heating and longitudinally or axially
stretching the catheter shaft, either prior to proceeding with the
other fabrication steps, or at any desired point in the process.
Such stretching, for example, may be used to reduce the diameter of
the catheter shaft.
Next, the outer walls of the lumens are removed as appropriate from
the point at which the distal end of each balloon is to be located
and extending to the distal end of the catheter. In other words,
some of the lumens may be shortened by removing the outer wall
thereof so the lumen does not extend all the way to the distal end
of the catheter. This removal step is preferably accomplished by
cutting away the outer lumen wall. With each lumen terminating at
the point where the end of the balloon formed from the outer wall
of the lumen is to have its distal end, the open lumen ends are
sealed to either the underlying catheter shaft or to the underlying
lumen wall, as appropriate. In axial torque multiple balloon
catheters, the distal end of at least one of the lumens is sealed
to the axial torque wire itself either at this point or after
blowing the balloons.
In both the extrusion process and the molding process, the outer
walls of the lumens adjacent to their sealed, distal ends are then
heated to soften the thermoplastic material to the point where it
can be blown to form balloons. The balloons may advantageously be
blown one at a time inside a die having appropriate dimensions. The
dimensions of the finished balloon are determined by the dimensions
of the interior of the die. A heated die is preferred. Measures
well known in the art to prevent sticking of overlapping balloon
layers and sticking of balloon material to the die should be
employed. Moreover, while applying pressure to one lumen to blow
the outer wall thereof at the distal end thereof into a balloon,
collapse of other lumens must be prevented, either by applying a
lesser pressure to those lumens or by inserting a solid or
particulate filler or a trochar into the lumen. Blowing of
innermost balloons first is preferred, with an appropriate
adhesion-prevention powder (such as talcum powder), if required,
inside lumens overlying the balloon being blown. The overlying
balloons are then blown in sequence from innermost to
outermost.
In some instances and with some thermoplastic materials, stiffening
of the catheter shaft itself may be desirable. This is particularly
true with steerable guidewire-type catheters. Such stiffening may
be accomplished in any of a number of ways, such as by inserting a
stiffening material, solid, tubular, or any other suitable
geometry, into one of the lumens or incorporating the stiffening
material directly into the catheter shaft. Alternatively, the
stiffening material may be bonded to the outside of the catheter
shaft or the catheter shaft may be completely surrounded by the
stiffening material.
The aforementioned technique, while described in terms of
multiple-balloon catheters, may also be used to fabricate steerable
guidewire-type single balloon catheters.
IV.
Surgical Procedure Utilizing Limacon Balloon Catheters
In connection with the new catheter designs set forth above, a
surgical procedure utilizing those balloons to permit multi-vessel
coronary or peripheral angioplasty in a greatly reduced time as
compared to current techniques has been developed. This new
percutaneous transluminal coronary angioplasty (PTCA) technique for
multi-vessel disease is explained below in connection with a
schematic drawing illustrating particular locations of
cardiovascular disease. Of course, it will be understood that the
present technique can be utilized, in one form or another, with any
of the multiballoon catheter designs disclosed in the present
application, and that utilization of the technique is not limited
to the particular disease locations exemplified and illustrated in
the following discussion and the accompanying figure.
A model of the left coronary system having multiple lesions in
vessels of various diameter has been adopted for purposes of this
description. The diagram used in this description, FIG. 34,
represents a hypothetical but not unrealistic case. It should be
understood, of course, that the new surgical technique described
herein can be used in either the left or the right coronary artery,
or in both arteries as a part of the same surgical procedure. What
is critical for successful dilation of the lesions in question is
that each dilation should be performed with a balloon having a
predetermined maximum inflated diameter matching the native
diameter of the arterosclerotic vessel.
FIG. 34 is a diagram of the left coronary artery system. The left
main artery 110 branches into the left anterior descending (LAD)
artery 112, in which two arterosclerotic lesions are illustrated.
The first lesion 114 is located in the proximal portion of the LAD,
in a vessel having a native diameter of 3.0 mm. The second lesion
116 is located in the distal LAD in a vessel having a native
diameter of 2.0 mm. The circumflex artery 120 branches off of the
left main artery 110. A third lesion 122 is illustrated in the
circumflex artery 120, in a vessel having a native diameter of 2.0
mm. Finally, the obtuse marginal artery 124 (OMA) branches from the
circumflex artery 120. A fourth lesion 126 is illustrated in the
OMA 124 in a vessel having a native diameter of 2.5 mm.
With currently available PCTA techniques, three separate PCTA
catheters would be needed to perform multivessel PTCA in this
model. One of the catheters required would have a balloon of 3.0
mm, one a balloon of 2.5 mm, and one a balloon of 2.0 mm. With the
procedure of the present invention, only one specially designed
PCTA catheter is needed. As a result, the necessity for catheter
exchange is eliminated, and the amount of X-ray exposure, the
amount of contrast material injected, and the length of the PCTA
procedure are all reduced.
The present invention may be used in the left coronary artery
system having the lesions illustrated in FIG. 31 in the following
way.
The patient is prepared and a conventional guiding catheter is
inserted through the aorta into the left main artery 110. Any
suitable triple balloon catheter (or a dual balloon catheter having
two partially-overlapping balloons on opposite sides of the
catheter shaft) of the type described previously herein is advanced
through the guiding catheter and into the LAD 112. The triple
balloon catheter is provided with a first balloon having a maximum
inflated diameter of 2.0 mm, a second balloon having a maximum
inflated diameter of 2.5 mm, and a third balloon (or two combined
balloons) having a maximum inflated diameter of 3.0 mm. Of course,
all three balloons have been deflated with negative pressure as the
catheter is advanced into the first lesion 114 in the LAD 112.
When the 3.0 mm third balloon is properly positioned inside the
first lesion 114, as verified by radiography showing the location
of the radiopaque marker inside the third balloon, the third
balloon is selectively inflated while the other balloons remain
collapsed. When proper dilation of the lesion 114 has been
achieved, the third balloon is deflated by applying negative
pressure to the third lumen. The balloon catheter is then advanced
to the next target lesion with all three balloons completely
deflated.
The balloon catheter is next advanced distally into the LAD 112
until the 2.0 mm first balloon is positioned inside the second
lesion 116. Once the deflated 2.0 mm first balloon is centered in
the second lesion 116, the first balloon is inflated to dilate the
second lesion 116.
When the lesion 116 has been fully dilated by inflation of the
first balloon, negative pressure is applied to fully deflate the
first balloon. The catheter is then retracted back to the left main
artery 110 and, through use of a steerable guidewire, is then
threaded into the obtuse marginal artery 124. Because the fourth
lesion 126 in the obtuse marginal artery 124 is in a vessel having
a native diameter of 2.5 mm, the second balloon having a maximum
inflated diameter of 2.5 mm is positioned inside the fourth lesion
126. The second balloon is then fully inflated to dilate the lesion
126, and is then collapsed as discussed in connection with the
previous dilations. The catheter is the withdrawn from the obtuse
marginal artery 124 and is inserted into the third lesion 122 in
the circumflex artery 120. The third lesion 122, in a vessel having
a native diameter of 2.0 mm, is dilated with the first balloon in
the same manner as was described in connection with the second
lesion 116.
The balloon catheter and the guiding catheter are then withdrawn
and the procedure is completed in accordance with standard PCTA
techniques.
Although the technique has been described in connection with the
left coronary artery system, it is equally applicable in PTCA of
the right coronary artery system and in valvular peripheral
angioplasty.
Because both the right and the left coronary artery systems are
equally susceptible to arterosclerotic disease, often patients will
have disease in both coronary arteries at the same time. As long as
the lesions are accessible to balloon angioplasty, they may be
conveniently and efficiently dilated by the technique described
herein using the multi-balloon catheter. The same balloon catheter
can be used in both arteries. However, it will typically be
necessary to exchange the guiding catheter if the procedure
involves a shift from one (left) coronary artery to the other
(right) coronary artery. The principle of effective balloon
catheter utilization is the same in the two arteries. However, in
order to increase efficiency, guiding catheters changed from one
artery to the other should be moved in such as way as to avoid a
return to a vessel that has previously been entered. This is
because each time the procedure is shifted from one artery to the
other, it is necessary to exchange the guiding catheter.
The present invention permits full and effective dilation of some
lesions that cannot effectively be dilated with a single balloon
catheter. In some cases of advanced arterosclerotic disease, a
lesion may result in such a reduced diameter that an angioplasty
balloon having a maximum inflated diameter the same as the diameter
of the native vessel cannot be advanced into the lesion. In this
case, a multi-balloon catheter made in accordance with the present
invention may be used to good effect. The low profile distal
balloon on the catheter, having an inflated diameter less than the
native diameter of the vessel, can be advanced into the lesion and
inflated to partially dilate the lesion so that the
appropriately-sized balloon can be placed inside the lesion and the
lesion can be fully dilated. Thus, tight lesions can be predilated
with a small balloon first, so that dilation of the lesions can be
completed with the larger balloon. It is estimated that 20-25% of
the single lesion cases in which balloon angioplasty is now
performed currently require a second balloon catheter because the
originally-selected balloon catheter is too large to cross the
lesion. With the present invention, these constricted single-lesion
dilations can now be performed with a single multi-balloon
catheter.
Thus, in accordance with one aspect of the procedure of the present
invention requires advancing a multi-balloon angioplasty catheter
of the type described herein having a plurality of
differently-sized balloons into the vessel to be dilated, dilating
a first lesion with a balloon having a first diameter, dilating a
second lesion with a balloon having a second diameter, and,
optionally, dilating a third lesion with a third balloon (or two
combined balloons) having a predetermined third diameter
appropriate for the third lesion.
In accordance with another aspect of the procedure of the present
invention, a single lesion may be dilated with a multi-balloon
catheter of the type described herein by advancing a first balloon
having a predetermined first diameter into the lesion, and dilating
the lesion with the first balloon, and then advancing a second
balloon into the lesion, wherein the second balloon has a maximum
inflated diameter larger than the maximum inflated diameter of the
first balloon, and then dilating the lesion with the second
balloon.
* * * * *